WIP add json-schema grammar test from llama.cpp

[marcnnn]

This commit adds tests for all grammar from
https://github.com/ggerganov/llama.cpp/blob/master/tests/test-json-schema-to-grammar.cpp

Many fail because the regex operator to repeat
{from,to} many times seems not implemented.

And some other problems.

@seanmor5 Thanks for all your work!

I would love to help with elixir-nx/bumblebee#354, but to get into understanding the difficulties I started here.

To get to the goal of Constrained sampling with rich JSON-schema support for tool calling in Elixir.

Since you have no License on the Project, is adding the grammars from the llama.cpp (MIT License) code okay for you?

[seanmor5]

@marcnnn Thank you for including these! I can look at adding {from, to} support. I think it's fine adding grammars from llama.cpp as well

This library is unfinished, but the idea was to be able to parse EBNF grammars into a state that could basically be used as a state machine during sampling. There are some challenges in Nx specifically that make this more difficult, specifically that each input to a generation algorithm needs to be a tensor with a static shape. I haven't had time to look at this problem in awhile, but I can assist if it's something you're interested in working on! I originally took inspiration from a PR in the huggingface repo; however, I think there are other approaches that are worth exploring from vllm and elsewhere. I am in the EEF ML Slack if you want to ping me there to chat about how we can achieve this